KR102551206B1 - Apparatus and method for mitigating interference in wirleess communicnation system - Google Patents

Abstract

In a chipset, the present invention detects interference characteristics of neighboring cells corresponding to preset groups, and performs an interference whitening operation based on the interference characteristics, and the groups are preset. The time period occupied by the first reference signal area is generated by dividing, or the frequency band occupied by the first reference signal area is divided and generated, or the time period occupied by the second reference signal area is divided and generated. , The frequency band occupied by the second reference signal region is wider than the frequency band occupied by the first reference signal region.

Description

Apparatus and method for mitigating interference in a wireless communication system

The present invention relates to an apparatus and method for mitigating interference in a wireless communication system, and more particularly, to an apparatus and method for mitigating interference based on reference signal grouping in a wireless communication system.

In general, improving system performance is a very important issue in a wireless communication system, and thus, various methods for improving system performance have been proposed. One of the various methods proposed to improve system performance is a method of mitigating interference.

Various methods of mitigating the interference have also been proposed, and one of them is an interference whitening method. As an example, an interference whitening scheme used in a long-term evolution (LTE, hereinafter referred to as “LTE”) mobile communication system will be described as follows. Hereinafter, for convenience of description, the interference whitening method used in the LTE mobile communication system will be referred to as an “LTE interference whitening method”.

First, the LTE interference whitening method is a reference signal supported in the LTE mobile communication system, for example, a common reference signal (CRS, hereinafter referred to as "CRS") or a demodulation reference signal (DMRS, hereinafter) (referred to as “DMRS”) to detect statistical characteristics of an interference signal, for example, a variance matrix, by using a plurality of samples, such as a minimum mean square error (MMSE, hereinafter) It is a method of mitigating an interference signal based on a method (referred to as "MMSE") or the like. Here, interference signal measurement for reference signals such as CRS or DMRS is mainly performed in units of subframes. The reason why interference signal measurement for reference signals is performed in units of subframes is that in the LTE mobile communication system, the base station This is because the (base station: BS) allocates resources in units of subframes.

However, in the recent LTE mobile communication system, a synchronization difference between transmission signals of base stations in one terminal occurs by more than several symbols due to various parameters such as network delay between base stations or signal transmission delay according to a distance difference between base stations. Not only cases are emerging as new issues, but cases such as the above often occur in real fields.

In this way, when a synchronization difference between transmission signals of base stations in one terminal occurs by several symbols or more, if interference is measured in units of subframes as in the LTE interference whitening method, interference is inaccurately measured, and the inaccurate interference measurement results. Significant deterioration in reception performance may occur for data affected by interfering signals out of synchronization.

Accordingly, there is a need for a method for efficiently mitigating interference in a wireless communication system.

On the other hand, the above information is presented only as background information to help the understanding of the present invention. No determination has been made, nor is any assertion made, as to whether any of the foregoing is applicable as prior art with respect to the present invention.

An embodiment of the present invention proposes an apparatus and method for mitigating interference in a wireless communication system.

In addition, an embodiment of the present invention proposes an apparatus and method for mitigating interference based on reference signal grouping in a wireless communication system.

In addition, an embodiment of the present invention proposes an apparatus and method for mitigating interference based on interference signal synchronization in a wireless communication system.

According to one embodiment of the present invention; In a chipset, interference characteristics of neighboring cells are detected according to preset groups, and an interference whitening operation is performed based on the interference characteristics. It is generated by dividing the time period occupied by one reference signal area, or by dividing the frequency band occupied by the first reference signal area, or by dividing the time period occupied by the second reference signal area. The frequency band occupied by the 2 reference signal areas is wider than the frequency band occupied by the first reference signal area.

According to one embodiment of the present invention; A method of operating a device for mitigating interference, comprising: detecting interference characteristics of neighboring cells corresponding to preset groups, and performing an interference whitening operation based on the interference characteristics, The groups are generated by dividing a time period occupied by a preset first reference signal area, by dividing a frequency band occupied by the first reference signal area, or by dividing a time period occupied by a second reference signal area. The frequency band occupied by the second reference signal area is wider than the frequency band occupied by the first reference signal area.

An embodiment of the present invention has an effect of enabling interference mitigation in a wireless communication system.

In addition, an embodiment of the present invention has an effect of enabling interference mitigation based on reference signal grouping in a wireless communication system.

In addition, an embodiment of the present invention has an effect of enabling interference mitigation based on interference signal synchronization in a wireless communication system.

Also other aspects as described above, features and benefits of certain preferred embodiments of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings:
1A is a diagram schematically illustrating a CRS when one antenna port is used in an LTE mobile communication system according to an embodiment of the present invention;
1B is a diagram schematically illustrating a CRS when two antenna ports are used in an LTE mobile communication system according to an embodiment of the present invention;
1C is a diagram schematically illustrating a CRS when 4 antenna ports are used in an LTE mobile communication system according to an embodiment of the present invention;
2 is a diagram schematically illustrating an interference environment when frame synchronization of an interfering base station and frame synchronization of a serving base station coincide in an LTE mobile communication system according to an embodiment of the present invention;
3 is a diagram schematically illustrating an example of an internal structure of a receiving device in an LTE mobile communication system according to an embodiment of the present invention;
4A and 4B are diagrams schematically illustrating an example of an interference whitening process in an LTE mobile communication system according to an embodiment of the present invention;
5 schematically illustrates an example of a CRS grouping process for an interference whitening process in a subframe asynchronous situation in an LTE mobile communication system according to an embodiment of the present invention;
6a to 6g schematically illustrate other examples of a CRS grouping process for an interference whitening process in a subframe asynchronous situation in an LTE mobile communication system according to an embodiment of the present invention;
7 is a diagram schematically illustrating another example of an internal structure of a receiving device in an LTE mobile communication system according to an embodiment of the present invention;
8A and 8B are diagrams schematically illustrating another example of an interference whitening process in an LTE mobile communication system according to an embodiment of the present invention;
9 is a flowchart schematically illustrating a process of determining a CRS group in an LTE mobile communication system according to an embodiment of the present invention;
10 is a diagram schematically illustrating another example of a CRS grouping process for an interference whitening process in an asynchronous subframe situation in an LTE mobile communication system according to an embodiment of the present invention;
11 is a diagram schematically illustrating an example of an internal structure of a communication device in an LTE mobile communication system according to various embodiments of the present invention;
12 is a diagram schematically illustrating an example of an internal structure of a terminal including a communication device in an LTE mobile communication system according to various embodiments of the present invention;
13 is a diagram schematically illustrating an internal structure of a base station in a wireless communication system according to various embodiments of the present invention.
It should be noted that throughout the drawings, like reference numbers are used to show the same or similar elements, features and structures.

The following detailed description with reference to the accompanying drawings will aid in a comprehensive understanding of various embodiments of the present disclosure, which is defined by the claims and their equivalents. The detailed description that follows includes numerous specific details for an understanding thereof, which are to be regarded merely as examples. Accordingly, those skilled in the art will recognize that various changes and modifications of the various embodiments described herein may be made without departing from the scope and spirit of the present disclosure. Also, descriptions of well-known functions and configurations may be omitted for clarity and conciseness.

The terms and words used in the following detailed description and claims are not limited in their literal sense, but are simply used to enable a clear and consistent understanding of the present disclosure by the inventors. Accordingly, to those skilled in the art, the following detailed description of various embodiments of the present disclosure is provided for illustrative purposes only, and defines the present disclosure as defined by the appended claims and their equivalents. It should be clear that it is not provided to do so.

In addition, it will be understood that singular expressions such as “above” and “above” include plural expressions in this specification unless clearly indicated otherwise. Thus, as an example, a “component surface” includes one or more component representations.

In addition, terms including ordinal numbers, such as first and second, may be used to describe various components, but the components are not limited by the terms. These terms are only used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention. The terms and/or include any combination of a plurality of related recited items or any of a plurality of related recited items.

In addition, terms used in this specification are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "include" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

In addition, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be understood to have meanings consistent with meanings in the context of related art.

According to various embodiments of the present invention, an electronic device may include a communication function. For example, electronic devices include a smart phone, a tablet, a personal computer (PC, hereinafter referred to as a 'PC'), a mobile phone, a video phone, and an e-book reader (e -book reader), desktop PC, laptop PC, netbook PC, personal digital assistant (PDA, hereinafter referred to as 'PDA'), and portable A portable multimedia player (PMP, hereinafter referred to as 'PMP'), an mp3 player, a mobile medical device, a camera, and a wearable device (for example, a head-mounted A device (head-mounted device: HMD, for example referred to as 'HMD'), electronic clothes, electronic bracelets, electronic necklaces, electronic appcessories, electronic tattoos, or smart watches ) and so on.

According to various embodiments of the present invention, an electronic device may be a smart home appliance having a communication function. For example, the smart household device includes a television, a digital video disk (DVD, hereinafter referred to as a 'DVD') player, an audio system, a refrigerator, an air conditioner, a vacuum cleaner, an oven, A microwave oven, a washer, a dryer, an air purifier, a set-top box, a TV box (eg, Samsung HomeSync ^TM , Apple TV ^TM , or Google TV ^TM ), and a game console (gaming console), electronic dictionary, camcorder, electronic photo frame, etc.

According to various embodiments of the present invention, an electronic device may include a medical device (eg, a magnetic resonance angiography (MRA), hereinafter referred to as 'MRA') device, and a magnetic resonance imaging method. : MRI, hereinafter referred to as "MRI"), computed tomography (CT, hereinafter referred to as 'CT') device, imaging device, or ultrasound device), navigation device and , a global positioning system (GPS, hereinafter referred to as 'GPS') receiver, an event data recorder (EDR, hereinafter referred to as 'EDR'), and a flight data recorder (flight data recorder) recorder: FDR, hereinafter referred to as 'FER'), automotive infotainment device, navigation electronic device (eg, navigation navigation device, gyroscope, or compass), and avionics electronic device It can be a security device, an industrial or consumer robot, and the like.

According to various embodiments of the present invention, an electronic device includes furniture, a part of a building/structure, an electronic board, an electronic signature receiving device, a projector, and various measuring devices (eg, water, electricity, gas or electromagnetic wave measuring devices), etc.

According to various embodiments of the present invention, an electronic device may be a combination of devices as described above. In addition, it will be apparent to those skilled in the art that the electronic device according to the preferred embodiments of the present invention is not limited to the devices described above.

According to various embodiments of the present invention, a transmitting device may be a terminal or a base station (BS). Here, it goes without saying that the terminal may be implemented with one chipset.

Also, according to various embodiments of the present invention, a receiving device may be a terminal or a BS.

According to various embodiments of the present disclosure, a terminal may be, for example, an electronic device.

In addition, in various embodiments of the present invention, a terminal includes a mobile station (MS, hereinafter referred to as "MS"), a user equipment (UE), a wireless terminal, It should be noted that terms such as mobile device and the like may be used interchangeably.

In addition, in various embodiments of the present invention, a base station includes a node B, an evolved node B (eNB, hereinafter referred to as “eNB”), and an access point (AP). , Hereinafter referred to as “AP”), it should be noted that terms such as the like can be used interchangeably.

In addition, in various embodiments of the present invention, serving base station may be used interchangeably with terms such as serving cell and the like, and adjacent base station may be interchanged with terms such as adjacent cell.

An embodiment of the present invention proposes an apparatus and method for mitigating interference in a wireless communication system.

In addition, an embodiment of the present invention proposes an apparatus and method for mitigating interference based on reference signal grouping in a wireless communication system.

In addition, an embodiment of the present invention proposes an apparatus and method for mitigating interference based on interference signal synchronization in a wireless communication system.

Meanwhile, an apparatus and method proposed in an embodiment of the present invention is a long-term evolution (LTE, hereinafter referred to as “LTE”) mobile communication system, and a long-term evolution-advanced (long-term evolution -advanced: LTE-A, hereinafter referred to as "LTE-A") mobile communication system, and licensed-assisted access (LAA, hereinafter referred to as "LAA") -LTE mobile communication system , high speed downlink packet access (HSDPA, hereinafter referred to as "HSDPA") mobile communication system, and high speed uplink packet access (HSUPA, hereinafter referred to as "HSUPA") ) Mobile communication system and high rate packet data (HRPD, hereinafter referred to as "HRPD") of the 3rd generation partnership project 2 (3GPP2, hereinafter referred to as "3GPP2") a) mobile communication system, 3GPP2 wideband code division multiple access (WCDMA, hereinafter referred to as "WCDMA") mobile communication system, and 3GPP2 code division multiple access (CDMA) , hereinafter referred to as "CDMA") mobile communication system, Institute of Electrical and Electronics Engineers (IEEE, hereinafter referred to as "IEEE") 802.16m communication system, and IEEE 802.16e communication system and an evolved packet system (EPS, hereinafter referred to as "EPS"), a mobile internet protocol (Mobile IP, hereinafter referred to as "Mobile IP") system, and digital multimedia broadcasting (digital multimedia broadcasting: DMB, hereinafter referred to as “DMB”) service, digital video broadcasting-handheld (DVP-H, hereinafter referred to as “DVP-H”), and mobile/ Mobile broadcasting services such as advanced television systems committee-mobile/handheld (ATSC-M/H, hereinafter referred to as "ATSC-M/H") services, and Internet protocol television : IPTV, hereinafter referred to as "IPTV") service, such as a digital video broadcasting system, and an MPEG media transport (moving picture experts group (MPEG) media transport: MMT, hereinafter referred to as "MMT") system, etc. Applicable to various wireless communication systems.

Hereinafter, for convenience of description, it will be assumed that a wireless communication system, for example, a cellular system, is a 3GPP LTE mobile communication system in an embodiment of the present invention.

First, in a cellular system, signals received by a terminal may include signals transmitted by neighboring base stations in addition to signals transmitted by a base station through which the terminal transmits and receives signals, for example, a serving base station.

In a general wireless communication system other than a cooperative communication system in which cooperative communication between base stations is supported, signals transmitted from neighboring base stations act as interference to terminals, and therefore, signals transmitted from neighboring base stations are transmitted between the terminal and the serving base station. interfering with communication.

Meanwhile, in a wireless communication system, when the strength of an interference signal is greater than the strength of a signal received from a serving base station according to the location or channel characteristics of a terminal, the terminal may experience serious communication performance degradation. In particular, a detector and a decoder included in a terminal using a plurality of receiving antennas generate additive white Gaussian noise (AWGN, hereinafter referred to as "AWGN") signals other than signals transmitted from the serving base station. , whereas signals received from neighboring base stations have correlation between antennas, an interference signal degrades detector and decoder performance. At this time, the correlation between the antennas is expressed as that the corresponding signal is colored, and when such coloration does not exist, the corresponding signal is expressed as whitened.

Meanwhile, an interference whitener may be used to mitigate a correlation characteristic between antennas of an interference signal. In general, the interference whitener uses a minimum mean square error (MMSE, hereinafter referred to as “MMSE”) method, and the interference whitener using the MMSE method measures statistical characteristics between antennas of an interference signal And, by inversely compensating the measured statistical characteristics, it is possible to provide a correlation between antennas, that is, a received signal and a channel value including only whitened interference signals and noise from which coloration is removed. The operation of the interference whitener can be expressed using equations, which will be described in detail as follows.

First, the received signal received from the terminal can be expressed as in Equation 1 below.

<Equation 1>

In Equation 1, y represents a received signal vector, H represents a channel matrix between the terminal and a serving base station, and x represents a transmitted signal vector.

In addition, in Equation 1, v can be expressed as in Equation 2 below.

<Equation 2>

In Equation 2, H _I denotes a channel matrix between an interfering base station, that is, a neighboring base station transmitting an interference signal to the terminal and the terminal, x _I denotes a transmission signal vector of the interference signal, and n is a noise vector. am. Here, the noise vector n has a circularly symmetric complex Gaussian characteristic.

Meanwhile, as described above, the interference whitener detects statistical characteristics between antennas of the interference signal. For example, based on a method of detecting a sample mean of a covariance matrix, the antenna of the interference signal Statistical characteristics can be detected. Here, a method of detecting the sample mean of the covariance matrix can be expressed as Equation 3 below.

<Equation 3>

In Equation 3, R represents the covariance matrix, σ ² denotes a variance value of the interference signal, and I denotes an identity matrix.

As shown in Equation 3 above, an operation of inversely compensating a received signal based on a sample mean of the covariance matrix is an interference whitening operation. Here, the interference whitening operation can be expressed as Equation 4 below.

<Equation 4>

In Equation 4, L ^-1 v represents the result of decompensating interference and noise from a neighboring cell, and the covariance matrix L ^-1 v of the modified interference and noise signal is calculated as an identity matrix. That is, the correlation between the receiving antennas is removed due to the effect of the inverse compensation, and this operation becomes an interference whitening operation. In Equation 4, W = L ^{- 1} represents a whitening filter coefficient, and in an embodiment of the present invention, Wy and WH will be defined as y _w and H _{w ,} respectively.

Meanwhile, the fact that the covariance matrix of the interference and noise signals is calculated as an identity matrix may mean that the received power for each receive antenna is equalized. As a result, this means that a signal in a form that is easy to be detected by a detector and a decoder can be provided. Therefore, it is necessary to estimate the covariance matrix of the interference signal defined by R , as shown in Equation 3 above.

Meanwhile, in a wireless communication system according to an embodiment of the present invention, in a multi-receive antenna environment, that is, in an environment in which a terminal uses a plurality of receive antennas, the terminal uses a covariance matrix of an interference signal to perform an interference whitening operation. Suggest ways to obtain Hereinafter, for convenience of explanation, it will be assumed that the wireless communication system is an LTE mobile communication system.

First, in the LTE mobile communication system, a measurement result of a reference signal (RS, hereinafter referred to as "RS") is used to detect characteristics of an interference signal as suggested in the interference whitening scheme. Here, the RS is a common reference signal (CRS, hereinafter referred to as "CRS") and a multimedia broadcast multicast service single frequency network according to its purpose and channel type. network: MBSFN, hereinafter referred to as "MBSFN") reference signal (multimedia broadcast multicast service single frequency network reference signal: MRS, hereinafter referred to as "MRS"), demodulation reference signal (DMRS, hereinafter referred to as It may be referred to as "DMRS"), channel status information interference measurement (CSI-IM, hereinafter referred to as "CSI-IM") signals, and the like.

On the other hand, in the LTE mobile communication system, since a base station and a terminal transmit a predetermined sequence as an RS at a predetermined location, the terminal measures the RS and transmits the RS to the antenna port of the base station and the reception included in the terminal. A channel between each of the antennas may be estimated, and statistical characteristics of an interference signal and a noise signal at each of the reception antennas included in the terminal may also be measured.

Here, the CRS according to the number of antenna ports in the LTE mobile communication system according to an embodiment of the present invention will be described with reference to FIGS. 1A to 1C.

First, referring to FIG. 1A , a CRS when one antenna port is used in an LTE mobile communication system according to an embodiment of the present invention will be described.

1A is a diagram schematically illustrating a CRS when one antenna port is used in an LTE mobile communication system according to an embodiment of the present invention.

Referring to FIG. 1A, the CRS shown in FIG. 1A assumes a normal cyclic prefix in one subframe and represents a CRS when one antenna port is used. In FIG. 1A, each grid represents a resource element (RE, hereinafter referred to as “RE”), and R ₀ represents REs through which CRSs are transmitted.

In FIG. 1A, a CRS when one antenna port is used in an LTE mobile communication system according to an embodiment of the present invention has been described. Next, referring to FIG. 1B, in an LTE mobile communication system according to an embodiment of the present invention, The CRS when two antenna ports are used will be described.

1B is a diagram schematically illustrating a CRS when two antenna ports are used in an LTE mobile communication system according to an embodiment of the present invention.

Referring to FIG. 1B, the CRS shown in FIG. 1B assumes a normal cyclic prefix in one subframe and represents CRSs when two antenna ports are used. In FIG. 1B, each grid represents an RE, R ₀ represents REs to which a CRS mapped to antenna port 0 is transmitted, and R1 represents REs to which a CRS mapped to antenna port 1 is transmitted. As shown in FIG. 1B, the CRS mapped to antenna port 1 is not transmitted through REs through which the CRS mapped to antenna port 0 is transmitted, and the CRS mapped to antenna port 1 is transmitted through REs through which the CRS mapped to antenna port 1 is transmitted. A CRS mapped to 0 is not transmitted.

In FIG. 1B, a CRS in the case where two antenna ports are used in an LTE mobile communication system according to an embodiment of the present invention has been described. Next, referring to FIG. 1C, in an LTE mobile communication system according to an embodiment of the present invention, A CRS in the case where four antenna ports are used will be described.

1C is a diagram schematically illustrating a CRS when four antenna ports are used in an LTE mobile communication system according to an embodiment of the present invention.

Referring to FIG. 1c, first, the CRSs shown in FIG. 1c assume a normal cyclic prefix in one subframe and represent CRSs when four antenna ports are used. In FIG. 1C, each grid represents an RE, R ₀ represents REs to which a CRS mapped to antenna port 0 is transmitted, R ₁ represents REs to which a CRS mapped to antenna port 1 is transmitted, and R ₂ represents antenna port 2 represents REs to which the CRS mapped to is transmitted, and R3 represents REs to which the CRS mapped to antenna port 3 is transmitted. As shown in FIG. 1C, CRSs mapped to antenna ports 1 to 3 are not transmitted through REs to which CRSs mapped to antenna port 0 are transmitted, and REs to which CRSs mapped to antenna port 1 are transmitted. CRSs mapped to antenna 0 and antenna port 2 to antenna port 3 are not transmitted through antenna port 2, CRS mapped to antenna port 2 is transmitted through REs through which CRS mapped to antenna port 2 is transmitted CRS mapped to antennas 0 to 1 and antenna port 3 are transmitted Otherwise, CRSs mapped to antennas 0 to 2 are not transmitted through REs through which CRSs mapped to antenna port 3 are transmitted.

In Figures 1a to 1c, the CRS according to the number of antenna ports in the LTE mobile communication system according to an embodiment of the present invention has been described. Next, with reference to Figure 2, the LTE mobile communication system according to an embodiment of the present invention , an interference environment when the frame synchronization of the interfering base station and the frame synchronization of the serving base station coincide will be described.

2 is a diagram schematically illustrating an interference environment when frame synchronization of an interfering base station and frame synchronization of a serving base station coincide in an LTE mobile communication system according to an embodiment of the present invention.

Referring to FIG. 2, first, when the subframe timing of a signal received from an adjacent base station coincides with the subframe timing of a signal received from a serving base station, a CRS included in a control channel (CCH) region Samples may be used to estimate an interference signal for the CCH region, and CRS samples included in a synchronization channel (SCH, hereinafter referred to as “SCH”) region are used to estimate an interference signal for the SCH region can be used Here, the CRS samples refer to samples included in the CRS, and are transmitted in a preset CRS region, for example, a CRS region occupied by a preset number of symbols and a preset number of REs. do. And, it is assumed that the number of CRS samples is N.

For example, if a terminal receiving CRS through two antenna ports assumes that the signal received at the location where the n-th CRS sample is transmitted is y _n , the signal received at the location where the n-th CRS sample is transmitted is y _n can be expressed as in Equation 5 below.

<Equation 5>

In Equation 5, k represents a symbol index of a location where the n-th CRS sample is transmitted, and f represents a subcarrier index of a location where the n-th CRS sample is transmitted.

In addition, the terminal performs a blind detection operation when receiving a physical broadcast channel (PBCH, hereinafter referred to as "PBCH") signal from the base station during the initial access process, so that the terminal itself The number of antenna ports to be used can be obtained, and the location of the antenna ports to be used by the terminal itself can be obtained based on a cell identifier (ID, hereinafter referred to as "ID"). Here, the terminal uses a primary synchronization signal (PSS, hereinafter referred to as "PSS") and a secondary synchronization signal (SSS, hereinafter referred to as "SSS") during the initial access process The cell ID may be obtained when performing the detecting operation.

Meanwhile, in the LTE mobile communication system, when a normal subframe is used, CRSs corresponding to antenna port 0 and antenna port 1 are generated through symbol 0, symbol 4, symbol 7, and symbol 11 in the time domain. is sent Here, the position of the frequency domain where the CRS is transmitted in each symbol is the position of the frequency domain where the CRS corresponding to the antenna port 0 is transmitted in symbol 0 and symbol 7, RE {Cell ID %6} and RE {Cell ID %6 } + 6, and the positions of the frequency domain where the CRS corresponding to antenna port 1 is transmitted become RE {Cell ID % 6} + 3 and RE {Cell ID % 6} + 9. In contrast, in symbol 4 and symbol 11, the positions of the frequency domain where the CRS corresponding to antenna port 0 is transmitted are RE {Cell ID % 6} + 3 and RE {Cell ID % 6} + 9, and antenna port 1 The positions of the frequency domain where the corresponding CRS is transmitted are RE {Cell ID %6} and RE {Cell ID %6} + 6.

Meanwhile, interference characteristics of neighboring cells may be obtained based on CRS. As an example, the interference characteristic of the neighboring cell may be obtained based on a sampled covariance matrix (SCM, hereinafter referred to as "SCM"), and the SCM may be expressed as in Equation 6 below. .

<Equation 6>

In Equation 6 above, v _n may be obtained as shown in Equation 7 below in the n th CRS sample.

<Equation 7>

In Equation 7, y _k,f represents a received signal received in an RE occupied by a symbol index k and a subcarrier index f, and is referred to as a fast Fourier transform (FFT, hereinafter referred to as "FFT") ) can be obtained from the output.

In Equation 7, H _k,f represents a channel matrix in an RE occupied by a symbol index k and a subcarrier index f, and can be obtained based on a channel estimation result.

Also, in Equation 7, x _k,f represents a scrambling sequence transmitted in an RE occupied by a symbol index k and a subcarrier index f, that is, represents a CRS sample. Here, it goes without saying that the terminal knows in advance the CRS to be used by the terminal through communication with the base station.

Next, an example of an internal structure of a receiving device in an LTE mobile communication system according to an embodiment of the present invention will be described with reference to FIG. 3 .

3 is a diagram schematically illustrating an example of an internal structure of a receiving device in an LTE mobile communication system according to an embodiment of the present invention.

Referring to FIG. 3 , the receiving device includes an FFT unit 311 , a channel estimator 313 , an interference whitener 315 and a symbol detector 325 . In addition, the interference whitener 315 includes an SCM generator 317, a whitening filter generator 319, a whitening filter buffer 321, and an interference whitening unit 323.

First, the FFT unit 311 generates a time domain signal by performing an FFT operation on a received signal, and outputs the generated time domain signal y to the channel estimator 313 . The channel estimator 313 estimates a channel matrix H based on the signal y output from the FFT unit 311, and outputs the estimated channel matrix H to the interference whitener 315.

Meanwhile, the SCM generator 317 calculates SCM R as described in Equations 6 and 7 based on the signal y output from the FFT unit 311 and the channel matrix H output from the channel estimator 313 and outputs the generated SCM R to the whitening filter generator 319. The whitening filter generator 319 generates whitening filter coefficients W based on the SCM R output from the SCM generator 317, and outputs the generated whitening filter coefficients W to the whitening filter buffer 321. The whitening filter buffer 321 buffers the whitening filter coefficient W and outputs it to the interference whitening unit 323, and the interference whitening unit 323 buffers the signal y output from the FFT unit 311 and the channel An interference whitening operation is performed based on the channel matrix H output from the estimator 313 and the whitening filter coefficient W to detect y _w and H _w , and the detected y _w and H _w are sent to the symbol detector 325 print out The symbol detector 325 performs a symbol detection operation based on y _w and H _w .

Meanwhile, in FIG. 3, a case in which the receiver is implemented as separate units such as the FFT unit 311, the channel estimator 313, the interference whitener 315, and the symbol detector 325 is shown. , the receiving device can be implemented in a form in which at least two of the FFT unit 311, the channel estimator 313, the interference whitener 315, and the symbol detector 325 are integrated into one unit.

Also, the receiver may be implemented with one chipset or one processor.

In FIG. 3, an example of an internal structure of a receiving device in an LTE mobile communication system according to an embodiment of the present invention has been described, and then referring to FIGS. 4A and 4B, LTE mobile communication according to an embodiment of the present invention An example of an interference whitening process in a system will be described.

4A and 4B are diagrams schematically illustrating an example of an interference whitening process in an LTE mobile communication system according to an embodiment of the present invention.

Referring to FIGS. 4A and 4B , in step 411, the receiving device sets the value of the symbol index to 0 and proceeds to step 413. In step 413, the receiving device checks whether the symbol index of the corresponding symbol is 0. If the symbol index of the corresponding symbol is 0 as a result of the checking, the receiving device proceeds to step 415. Here, the reason for checking whether the symbol index of the corresponding symbol is 0 is to check whether the corresponding resource region is a CCH region.

In step 415, the receiving device sets the antenna port index to 0, sets SCM R to 0, and proceeds to step 417. In step 417, the receiving device sets the CRS index to 0 and proceeds to step 419. In step 419, the receiving device proceeds to step 421 after calculating n = y - Hx. In step 421, the receiving device accumulates SCM R and proceeds to step 423. In step 423, the receiving device increases the CRS index by a preset value, for example, 1, and then proceeds to step 425. In step 425, the receiving device checks whether the CRS index is less than 2. Here, the reason for checking whether the CRS index is less than 2 is because it is assumed that two CRS samples are transmitted per symbol in the LTE mobile communication system. As a result of the check, if the CRS index is less than 2, the receiving device returns to step 419.

Meanwhile, as a result of checking in step 425, if the CRS index is not less than 2, the receiving device proceeds to step 427. In step 427, the receiving device increases the antenna port index by a preset value, for example, 1, and then proceeds to step 429. In step 429, the receiving device checks whether the antenna port index is less than 2. Here, the reason for checking whether the antenna port index is less than 2 is because it is assumed that two antenna ports are used in the LTE mobile communication system. As a result of the check, if the antenna port index is less than 2, the receiving device returns to step 417.

Meanwhile, as a result of the check in step 429, if the antenna port index is not less than 2, the receiving device proceeds to step 431. In step 431, the receiving device returns to step 413 after increasing the symbol index by a preset value, for example, 1. In addition, as a result of the check in step 429, if the antenna port index is not less than 2, the receiving device proceeds to step 433. In step 433, the receiving device determines the accumulated SCM R as the SCM R for the CCH region.

Meanwhile, as a result of checking in step 413, if the symbol index of the corresponding symbol is not 0, that is, if the corresponding resource region is an SCH region, the receiving device proceeds to step 435. In step 435, the receiving device sets SCM R to 0 and proceeds to step 437. In step 437, the receiving device sets the antenna port index to 0 and proceeds to step 439. In step 439, the receiving device sets the CRS index to 0 and proceeds to step 441. In step 441, the receiving device proceeds to step 443 after calculating n = y - Hx. In step 443, the receiving device accumulates SCM R and proceeds to step 445. In step 445, the receiving device increases the CRS index by a preset value, for example, 1, and then proceeds to step 447. In step 447, the receiving device checks whether the CRS index is less than 2. As a result of the check, if the CRS index is less than 2, the receiving device returns to step 441.

Meanwhile, as a result of checking in step 447, if the CRS index is not less than 2, the receiving device proceeds to step 449. In step 449, the receiving device increases the antenna port index by a preset value, for example, 1, and then proceeds to step 451. In step 451, the receiving device checks whether the antenna port index is less than 2. As a result of the check, if the antenna port index is less than 2, the receiving device returns to step 439.

Meanwhile, as a result of the check in step 451, if the antenna port index is not less than 2, the receiving device proceeds to step 453. In step 453, the receiving device increases the symbol index by a preset value, for example, 1, and then proceeds to step 455. In step 455, the receiving device checks whether the symbol index is less than 4. As a result of the check, if the symbol index is less than 4, the receiving device returns to step 437.

Meanwhile, as a result of the check in step 455, if the symbol index is not less than 4, the receiving device proceeds to step 457. In step 457, the receiving device determines the accumulated SCM R as the SCM R for the SCH region.

Meanwhile, in the interference whitening process shown in FIGS. 4A and 4B, it is assumed that there are two CRSs corresponding to one antenna port per symbol, and frequency division duplexing (FDD, hereinafter referred to as “FDD”) is performed. It is assumed that a normal cyclic prefix (NCP, hereinafter referred to as “NCP”) subframe of “NCP” is assumed.

However, the interference whitening process proposed in an embodiment of the present invention is not only the NCP subframe, but also an extended cyclic prefix (ECP, hereinafter referred to as "ECP") subframe and time division duplexing of FDD (time division duplexing: TDD, hereinafter referred to as “TDD”) can be applied to subframes as well. However, it should be noted that the number and location of CRS symbols may be changed when the interference whitening process according to an embodiment of the present invention is applied to the ECP subframe of FDD and the subframe of TDD.

Meanwhile, even though FIGS. 4a and 4b illustrate an example of an interference whitening process in an LTE mobile communication system according to an embodiment of the present invention, various modifications may be made to FIGS. 4a and 4b. As an example, while successive steps are shown in FIGS. 4A and 4B , the steps described in FIGS. 4A and 4B may overlap, may occur in parallel, may occur in a different order, or may occur multiple times. is of course

An example of an interference whitening process in an LTE mobile communication system according to an embodiment of the present invention has been described in FIGS. 4A and 4B, and next, referring to FIG. 5, in an LTE mobile communication system according to an embodiment of the present invention An example of a CRS grouping process for an interference whitening process in an asynchronous subframe situation will be described.

5 is a diagram schematically illustrating an example of a CRS grouping process for an interference whitening process in a subframe asynchronous situation in an LTE mobile communication system according to an embodiment of the present invention.

Referring to FIG. 5, first, if the subframe timing of the interference signal and the subframe timing of the serving base station signal differ by more than several symbols, it is difficult to accurately estimate the interference signal because different types of interference exist in one subframe. It becomes difficult.

Therefore, in the current LTE mobile communication system, an interference model in case of assuming inter-cell sub-frame asynchronous has begun to be considered, and therefore, a need for an interference mitigation method in case of assuming inter-cell sub-frame asynchronous is emerging. In addition, interference signals applied only to some symbols may be generated not only when inter-cell subframe asynchronous occurs, but also due to near band interference or jamming signals existing in an adjacent frequency domain. Hereinafter, for convenience of explanation, a situation in which interference is applied to only some symbols will be referred to as a "partial interference situation".

Therefore, in an embodiment of the present invention, an RS grouping method is proposed to adaptively whiten interference in a subframe asynchronous situation such as an inter-cell subframe asynchronous situation or a partial interference situation, and a detailed description thereof is as follows.

First, the RS grouping method according to an embodiment of the present invention divides symbols into a plurality of, for example, two groups based on points at which subframe timings do not match, and based on only RSs corresponding to each group Information necessary for interference whitening can be obtained.

Therefore, as shown in FIG. 5, the receiving device has a total of three CRS groups for the serving base station, that is, the serving cell, that is, a CRS group corresponding to the CCH region and a CRS group corresponding to the preceding 1/2 of the SCH regions. The interference whitening process is performed based on a total of three CRS groups including a CRS group corresponding to the SCH region and a CRS group corresponding to the SCH region corresponding to the second half of the SCH regions.

In FIG. 5, an example of a CRS grouping process for an interference whitening process in a subframe asynchronous situation in an LTE mobile communication system according to an embodiment of the present invention has been described. Other examples of a CRS grouping process for an interference whitening process in a subframe asynchronous situation in an LTE mobile communication system according to an embodiment will be described.

6A to 6G are diagrams schematically illustrating other examples of a CRS grouping process for an interference whitening process in a subframe asynchronous situation in an LTE mobile communication system according to an embodiment of the present invention.

Referring to FIGS. 6A to 6G , it should be noted that examples of CRS grouping processes shown in FIGS. 6A to 6G are examples of CRS grouping processes when the number of antenna ports is two. As shown in FIGS. 6A to 6G, when the number of antenna ports is two, the number of CRS samples included in one CRS group according to the CRS grouping process can be 4, 8, or 12.

In addition, as shown in FIGS. 6A to 6G , there is no limitation on a reference symbol for generating CRS groups in the CRS grouping process, and the number of CRS groups may be 3 or more.

It can be seen that a total of 2 CRS groups are generated in FIGS. 6A to 6C, a total of 3 CRS groups are generated in FIGS. 6D to 6F, and a total of 4 CRS groups are generated in FIG. 6G.

In addition, in FIG. 6A, CRS group 1 includes 4 CRS samples, and CRS group 2 includes 12 CRS samples.

In addition, in FIG. 6B, CRS group 1 includes 8 CRS samples, and CRS group 2 includes 8 CRS samples.

In addition, in FIG. 6C, CRS group 1 includes 12 CRS samples, and CRS group 2 includes 4 CRS samples.

In addition, in FIG. 6D, CRS group 1 includes 4 CRS samples, CRS group 2 includes 8 CRS samples, and CRS group 3 includes 4 CRS samples.

Also, in FIG. 6E, CRS group 1 includes 4 CRS samples, CRS group 2 includes 4 CRS samples, and CRS group 3 includes 8 CRS samples.

In addition, in FIG. 6F, CRS group 1 includes 8 CRS samples, CRS group 2 includes 4 CRS samples, and CRS group 3 includes 4 CRS samples.

In addition, in FIG. 6G, each of CRS group 1 to CRS group 4 includes 4 CRS samples.

6a to 6g have described other examples of a CRS grouping process for an interference whitening process in a subframe asynchronous situation in an LTE mobile communication system according to an embodiment of the present invention. Next, referring to FIG. 7, one of the present invention Another example of an internal structure of a receiving device in an LTE mobile communication system according to an embodiment will be described.

7 is a diagram schematically illustrating another example of an internal structure of a receiving device in an LTE mobile communication system according to an embodiment of the present invention.

Referring to FIG. 7 , the receiving device includes an FFT unit 711, a channel estimator 713, an interference whitener 715, and a symbol detector 725. In addition, the interference whitener 715 includes an SCM generator 717, a whitening filter generator 719, a multiplexer 720, and a plurality of whitening filter buffers, for example, N whitening buffer filters, that is, whitening buffer filters. buffer filter 1 (721-1), ..., a whitening buffer filter N (721-N), a demultiplexer 722 and an interference whitening unit 723.

In an embodiment of the present invention, it is assumed that CRSs are generated with a total of N CRS groups for the interference whitening process, and therefore, the same number of whitening buffer filters as the number of CRS groups are applied to the interference whitener 715. included That is, since SCM and whitening filter coefficients are set differently for each of the N CRS groups, the interference whitener 715 includes the same number of whitening buffer filters as the number of CRS groups.

In addition, in an embodiment of the present invention, a case in which the interference whitener 715 includes the same number of whitening buffer filters as the number of CRS groups, but one whitening buffer filter is applied to the N CRS groups Of course, the corresponding whitening filter coefficients may be buffered.

First, the FFT unit 711 generates a time domain signal by performing an FFT operation on a received signal, and outputs the generated time domain signal y to the channel estimator 713. The channel estimator 713 estimates a channel matrix H based on the signal y output from the FFT unit 711 and outputs the estimated channel matrix H to the interference whitener 715.

Meanwhile, the SCM generator 717 generates SCM Rs as described in Equations 6 and 7 based on the signal y output from the FFT unit 711 and the channel matrix H output from the channel estimator 713. and outputs the generated SCM Rs to the whitening filter generator 719. Here, the SCM Rs are generated for the N CRS groups. That is, in an embodiment of the present invention, SCM is generated for each CRS group.

The whitening filter generator 719 generates whitening filter coefficients W based on the SCM Rs output from the SCM generator 717, and outputs the generated whitening filter coefficients W to the multiplexer 720. The multiplexer 720 multiplexes the signal output from the whitening filter generator 719, that is, multiplexes the whitening filter coefficients W output from the whitening filter generator 719 to form the whitening buffer filter 1 (721-1). , ... , output to the whitening buffer filter N (721-N). Here, the whitening filter coefficients W are generated for the N CRS groups. That is, in an embodiment of the present invention, whitening filter coefficients W are generated for each CRS group.

The whitening buffer filter 1 (721-1), ... , the whitening buffer filter N (721-N) buffers the corresponding whitening filter coefficient W and outputs it to the demultiplexer 722. The demultiplexer 722 demultiplexes the whitening filter coefficients W output from the whitening buffer filter 1 (721-1), ..., and the whitening buffer filter N (721-N) and outputs the demultiplexed output to the interference whitening unit 723. do. The interference whitening unit 723 performs an interference whitening operation based on the signal y output from the FFT unit 711, the channel matrix H output from the channel estimator 713, and the whitening filter coefficients W to obtain y _w and H _w are detected, and the detected y _w and H _w are output to the symbol detector 725 . The symbol detector 725 performs a symbol detection operation based on the y _ws and the H _ws .

Meanwhile, in FIG. 7, a case in which the receiver is implemented as separate units such as the FFT unit 711, the channel estimator 713, the interference whitener 715, and the symbol detector 725 is shown. , the receiving device can be implemented in a form in which at least two of the FFT unit 711, the channel estimator 713, the interference whitener 715, and the symbol detector 725 are integrated into one unit.

Also, the receiver may be implemented with one chipset or one processor.

In FIG. 7, another example of the internal structure of a receiving device in an LTE mobile communication system according to an embodiment of the present invention has been described. Next, referring to FIGS. 8A and 8B, LTE mobile communication according to an embodiment of the present invention Another example of an interference whitening process in a system will be described.

8A and 8B are diagrams schematically illustrating another example of an interference whitening process in an LTE mobile communication system according to an embodiment of the present invention.

Referring to FIGS. 8A and 8B , in step 811, the receiving device sets the value of the symbol index to 0 and proceeds to step 813. In step 813, the receiving device checks whether the symbol index of the corresponding symbol is 0. If the symbol index of the corresponding symbol is 0 as a result of the checking, the receiving device proceeds to step 815. Meanwhile, the operations of steps 815 to 833 are the same as the operations of steps 415 to 433 as described in FIGS. 4A and 4B, and therefore, detailed description thereof will be omitted herein.

Meanwhile, as a result of checking in step 813, if the symbol index of the corresponding symbol is not 0, that is, if the corresponding resource region is an SCH region, the receiving device proceeds to step 835. In step 835, the receiving device sets the CRS group index m to 1 (m = 1), sets R (1), the SCM R for CRS group 1, to 0, and proceeds to step 837. In step 837, the receiving device sets the antenna port index to 0 and proceeds to step 839. In step 839, the receiving device sets the CRS index to 0 and proceeds to step 841. In step 841, the receiving device proceeds to step 843 after calculating n = y - Hx. In step 843, the receiving device accumulates SCM R (k) and proceeds to step 845. In step 845, the receiving device increases the CRS index by a preset value, for example, 1, and then proceeds to step 847. In step 847, the receiving device checks whether the CRS index is less than 2. Here, the reason for checking whether the CRS index is less than 2 is because it is assumed that two CRS samples are transmitted per symbol in the LTE mobile communication system. As a result of the check, if the CRS index is less than 2, the receiving device returns to step 841.

Meanwhile, as a result of checking in step 847, if the CRS index is not less than 2, the receiving device proceeds to step 849. In step 849, the receiving device increases the antenna port index by a preset value, for example, 1, and then proceeds to step 851. In step 851, the receiving device checks whether the antenna port index is less than 2. Here, the reason for checking whether the antenna port index is less than 2 is because it is assumed that two antenna ports are used in the LTE mobile communication system. As a result of the check, if the antenna port index is less than 2, the receiving device returns to step 839.

Meanwhile, as a result of the check in step 851, if the antenna port index is not less than 2, the receiving device proceeds to step 853. In step 853, the receiving device increases the symbol index by a preset value, for example, 1, and then proceeds to step 855. In step 855, the receiving device checks whether the symbol index is less than 4. As a result of the check, if the symbol index is not less than 4, the receiving device proceeds to step 857. In step 857, the receiving device determines the accumulated SCM R (M) as the SCM R (M) for the CRS group M of the SCH region.

Meanwhile, if the symbol index is less than 4 as a result of the check in step 855, the receiving device proceeds to step 859. In step 859, the receiving device checks whether the symbol index is included in symbol indexes corresponding to the CRS group m. As a result of the check, if the symbol index is included in the symbol indexes corresponding to the CRS group m, the receiving device returns to step 837.

Meanwhile, as a result of checking in step 859, if the symbol index is not included in symbol indices corresponding to the CRS group m, the receiving device assigns the accumulated SCM R (m) to CRS group m of the SCH region. Determined by SCM R (m) for

In addition, as a result of checking in step 859, if the symbol index is not included in the symbol indexes corresponding to the CRS group m, the receiving device proceeds to step 863. In step 863, the receiving device increases the value of the CRS group index m by a preset value, for example, by 1, and then proceeds to step 865. In step 865, the receiving device sets R (m), which is the SCM R for CRS group m, to 0, and proceeds to step 837.

Meanwhile, in the interference whitening process shown in FIGS. 8A and 8B, it is assumed that there are two CRSs corresponding to one antenna port per symbol, and an NCP subframe of FDD is assumed.

However, it goes without saying that the interference whitening process according to an embodiment of the present invention can be applied not only to the NCP subframe but also to the ECP subframe of FDD and the subframe of TDD. However, it should be noted that the number and location of CRS symbols may be changed when the interference whitening process according to an embodiment of the present invention belongs to the ECP subframe of FDD and the subframe of TDD.

Meanwhile, although FIGS. 8A and 8B show another example of an interference whitening process in an LTE mobile communication system according to an embodiment of the present invention, various modifications may be made to FIGS. 8A and 8B. As an example, while successive steps are shown in FIGS. 8A and 8B , the steps described in FIGS. 8A and 8B may overlap, may occur in parallel, may occur in a different order, or may occur multiple times. is of course

8A and 8B have described another example of an interference whitening process in an LTE mobile communication system according to an embodiment of the present invention, and next, referring to FIG. 9, in an LTE mobile communication system according to an embodiment of the present invention A method of determining a CRS group will be described.

9 is a flowchart schematically illustrating a process of determining a CRS group in an LTE mobile communication system according to an embodiment of the present invention.

Referring to FIG. 9 , first, in an embodiment of the present invention, a receiving device must detect whether synchronized interference or unsynchronized interference exists between different CRS groups. Hereinafter, for convenience of description, unsynchronized interference will be referred to as “unsynchronized interference”. In addition, when the synchronized or unsynchronized interference exists, the receiving device must detect at what symbol timing the synchronized or unsynchronized interference is received. This operation may be performed for each subframe or may be performed adaptively as needed.

However, if the receiving device accurately knows an asynchronous symbol timing offset between an adjacent interfering base station and a serving base station, CRS groups can be more accurately generated based on the symbol timing offset. Here, the receiving device detects the symbol timing offset based on information obtained by measuring timing offsets of neighboring base stations when the terminal performs a cell synchronization operation in a cell search step included in the initial access process. can do.

To explain this in more detail with reference to FIG. 9 , the receiving device first selects cell j from among candidate cells in step 911 and then proceeds to step 913 . In step 913, the receiving device performs an initial detection process, that is, a PSS detection process, and then proceeds to step 915. Here, a serving cell ID and a half frame position may be detected through the PSS detection process.

In step 915, the receiving device performs a fine detection process, that is, an SSS detection process. Here, through the SSS detection process, a neighbor cell ID, a cyclic prefix (CP, hereinafter referred to as "CP") type and frame position may be detected. Here, the CP type may be, for example, NCP or ECP.

The process including the PSS detection process and the SSS detection process is a cell search process, and through the above cell search process, the terminal determines cell IDs of base stations to which the terminal itself can access, CP type and frame position. can be obtained Here, the frame position becomes the symbol timing offset.

The symbol timing offset may be used to determine the unit in which the interference whitener performs the CRS grouping process in an asynchronous situation. Here, the cell search process is performed in the initial access process or periodic reconnection process of the terminal, and each time the cell search process is performed, including cell IDs of candidate base stations and frame position information corresponding to each of the candidate base stations You can create a list and manage the created list.

In FIG. 9, a process of determining a CRS group in an LTE mobile communication system according to an embodiment of the present invention has been described. Next, referring to FIG. 10, an asynchronous subframe in an LTE mobile communication system according to an embodiment of the present invention has been described. In this situation, another example of a CRS grouping process for an interference whitening process will be described.

10 is a diagram schematically illustrating another example of a CRS grouping process for an interference whitening process in an asynchronous subframe situation in an LTE mobile communication system according to an embodiment of the present invention.

Referring to FIG. 10, when CRSs are first divided into a plurality of CRS groups within one subframe, the number of CRS samples per CRS group is reduced compared to before the CRSs are divided into a plurality of CRS groups. Since the number of CRS samples decreases in this way, channel estimation performance for each CRS group may deteriorate.

Therefore, in an embodiment of the present invention, a CRS group extended in the frequency domain will be considered. That is, in an embodiment of the present invention, when generating a CRS group, a plurality of adjacent resource regions in the frequency domain are considered. In this case, when the adjacent cell interference signal has the same CRS structure for a plurality of resource regions, channel estimation performance increases. Here, the resource region may be, for example, a resource block (RB, hereinafter referred to as “RB”), and the RB includes at least one RE. And, in one embodiment of the present invention, it is assumed that a plurality of adjacent resource regions are considered in the frequency domain when generating the CRS group, but the CRS group is generated in consideration of non-adjacent and distributed resource regions in the frequency domain. Of course it can.

In conclusion, since the CRS grouping process proposed in an embodiment of the present invention can be flexibly extended not only in the time domain but also in the frequency domain, channel estimation performance can be increased.

It should be noted that the CRS grouping process shown in FIG. 10 is a CRS grouping process based on a frequency domain. That is, the CRS grouping process shown in FIG. 10 is a CRS grouping process when a plurality of RBs, for example, two RBs, for example, RB c and RB c + 1 are set as a CRS grouping unit in the frequency domain. You will have to do it. In addition, in FIG. 10, CRS samples included in one subframe in the time domain are divided into two CRS groups.

Meanwhile, in an embodiment of the present invention, generating a number of RBs as one CRS group in the frequency domain may be performed in every subframe, in a preset period, or as needed. . In addition, in an embodiment of the present invention, when the difference in interference characteristics between RBs is less than a preset threshold difference, a relatively large number of RBs are generated as a CRS group compared to when the difference in interference characteristics between the RBs is greater than or equal to the threshold value Thus, the number of CRS samples included in the CRS group may be increased.

Meanwhile, the CRS grouping process as proposed in an embodiment of the present invention includes not only CRS but also MRS, DMRS, channel status information-reference signal (CSI-RS, hereinafter referred to as “CSI-RS”). It goes without saying that it can also be applied to RSs such as a CSI-IM signal, etc.).

In one embodiment of the present invention, an RS suitable for a transmission mode defined in the LTE mobile communication system is selected, and an RS grouping process is performed corresponding to the selected RS.

On the other hand, in the LTE mobile communication system, interference can also be measured for data signals or control signals. For example, interference can be measured based on the demodulated data signal or control signal. In this case, also in one embodiment of the present invention Of course, the grouping process according to the above can be applied. That is, the target of the grouping process is only changed from RS to a data signal or a control signal, and the grouping process and interference mitigation operation based thereon are similar to the grouping process and interference mitigation operation proposed in an embodiment of the present invention. Here, the data signal may be, for example, a physical downlink shared channel (PDSCH, hereinafter referred to as “PDSCH”) signal. In addition, the control signal is, for example, a physical downlink control channel (PDCCH, hereinafter referred to as “PDCCH”) signal, or an enhanced physical downlink control channel (EPDCCH, hereinafter referred to as “EPDCCH”). EPDCCH") may be a signal.

In addition, although the CRS grouping process and interference mitigation operation have been described based on the LTE mobile communication system in an embodiment of the present invention, it can be applied to other communication systems as well as the LTE mobile communication system proposed in an embodiment of the present invention. is of course

In FIG. 10, another example of a CRS grouping process for an interference whitening process in an asynchronous subframe situation in an LTE mobile communication system according to an embodiment of the present invention has been described. An example of an internal structure of a communication device in an LTE mobile communication system according to an example will be described.

11 is a diagram schematically illustrating an example of an internal structure of a communication device in an LTE mobile communication system according to various embodiments of the present invention.

Referring to FIG. 11 , a communication device 1100 according to various embodiments of the present invention includes a transceiver 1111, a processor 1113, a memory 1115, and a sensor unit 1117. do.

The transmitter/receiver 1111 performs a communication operation between the communication device 1100 and external devices, for example, a terminal other than the terminal including the communication device 1100 and external devices such as a BS. . Of course, the transmitter/receiver 1111 may be used interchangeably with various terms such as "communication module" or "communication interface".

In addition, the transmitter/receiver 1111 may perform a communication operation with the external devices based on various communication methods, which will be described in detail as follows.

First, the transmitter/receiver 1111 may perform a communication operation with the external devices based on a wireless communication method, and the wireless communication method includes a cellular communication method, for example, an LTE method, an LTE-A method, CDMA method, WCDMA method, universal mobile telecommunications system (UMTS, hereinafter referred to as "UMTS") method, and wireless broadband (WiBro, hereinafter referred to as "WiBro") method and a cellular communication method such as a global system for mobile communications (GSM, hereinafter referred to as “GSM”) method.

In addition, the wireless communication method is a short-distance communication method, for example, a wireless fidelity (WiFi) method, a Bluetooth method, a near field communication (NFC, hereinafter referred to as "NFC") method, and a worldwide A short-distance wireless communication method such as a global navigation satellite system (GNSS, hereinafter referred to as "GNSS") may be included. Here, the GNSS includes, for example, at least one of GPS, Glonass (Global Navigation Satellite System), Beidou Navigation Satellite System (hereinafter referred to as “Beidou”), or Galileo, the European global satellite-based navigation system, depending on the region of use or bandwidth. can do. Hereinafter, in the present invention, "GPS" may be used interchangeably with "GNSS".

Also, the transmitter/receiver 1111 may perform a communication operation with the external devices based on a wired communication method. The wired communication method includes a universal serial bus (USB, hereinafter referred to as "USB") method, a high definition multimedia interface (HDMI, hereinafter referred to as "HDMI") method, RS It may include at least one of a -232 (recommended standard 232) method, a POTS (plain old telephone service) method, and the like.

In particular, the transmitter/receiver 1111 transmits/receives various signals and various messages related to an interference mitigation method according to various embodiments of the present invention, that is, a method for mitigating interference based on CRS grouping. Since various signals and various messages transmitted/received by the transmitter/receiver 1111 are the same as those described in FIGS. 1 to 10, a detailed description thereof will be omitted here.

In addition, the processor 1113 may include a communication processor (CP, hereinafter referred to as "CP"). According to various embodiments of the present invention, the processor 1113 may be a central processing unit (CPU) or an application processor (AP). It may further include one or more of (to be referred to). The processor 1113 may perform operations related to control and/or communication of at least one other unit included in the communication device 1100 or an operation related to data processing. According to various embodiments of the present invention, the term "processor", in some embodiments, may be used in various ways such as "control module", "control unit" or "controller". terms may be used interchangeably.

In particular, the processor 1113 controls an operation related to an interference mitigation scheme according to various embodiments of the present invention. Since operations related to the interference mitigation method according to various embodiments of the present invention are the same as those described in FIGS. 1 to 10 , a detailed description thereof will be omitted here.

The memory 1115 may include volatile and/or non-volatile memory. The memory 1115 may store, for example, instructions or data related to at least one other unit included in the communication device 1100 . According to various embodiments of the present invention, the memory 1115 may store software and/or programs. The programs, for example, kernel (kernel), middleware (middleware), application programming interface (application programming interface: API, hereinafter referred to as "API") and / or application program (or "application"), etc. can include In FIG. 11 , a case in which the memory 1115 is included in the communication device 1100 is illustrated, but this is only an example, and the communication device 1100 does not necessarily include the memory 1115 .

In particular, the memory 1115 stores various programs and various data related to operations related to an interference mitigation scheme according to various embodiments of the present invention. Operations related to the indoor location estimation method according to various embodiments of the present invention are the same as those described with reference to FIGS. 1 to 10 , so detailed description thereof will be omitted here.

The sensor unit 1117 may include an inertial sensor, and the inertial sensor may include an acceleration sensor, an angular velocity sensor, and a magnetic field sensor. In particular, sensor information sensed by the sensor unit 1117 is transmitted to the processor 1113, and the processor 1113, based on the sensor information transmitted from the sensor unit 1117, provides various embodiments of the present invention. Performs an operation related to an interference mitigation method according to.

Meanwhile, FIG. 11 shows a case in which the communication device 1100 is implemented as separate units such as the transmitter/receiver 1111, processor 1113, memory 1115, and sensor unit 1117. However, the communication device 1100 can be implemented in a form in which at least two of the transmitter/receiver 1111, processor 1113, memory 1115, and sensor unit 1117 are integrated into one unit. is of course

Also, the communication device 600 may be implemented with one chipset.

In FIG. 11, an example of the internal structure of a communication device in the LTE mobile communication system according to various embodiments of the present invention has been described. Next, with reference to FIG. 12, the LTE mobile communication system according to various embodiments of the present invention has been described. , an example of an internal structure of a terminal including a communication device will be described.

12 is a diagram schematically illustrating an example of an internal structure of a terminal including a communication device in an LTE mobile communication system according to various embodiments of the present invention.

Referring to FIG. 12 , a terminal 1200 according to various embodiments of the present disclosure may include a communication device 1100, a display 1211, and an input/output interface 1213.

The communication device 1100 may communicate with external electronic devices, for example, the electronic device 1230 and the electronic device 1240 through the network 1220, and may also communicate with the BS 1210. Since the communication device 1100 is the same as that described in FIG. 11, a detailed description thereof will be omitted here.

The display 1211 may be implemented in various forms, and as an example, a liquid crystal display (LCD, hereinafter referred to as "LCD"), a light-emitting diode (LED, hereinafter referred to as "LCD"), and the like. referred to as "LED") displays, organic light-emitting diode (OLED) displays, and microelectromechanical systems (MEMS, hereinafter referred to as "MEMS") displays. It can be implemented in various forms such as a display, an electronic paper display, and the like.

In addition, the display 1211 may display various types of content, such as text, image, video, icon, symbol, and the like. Also, the display 1211 may include a touch screen, and thus may receive a touch, gesture, proximity, or hovering input.

The input/output interface 1213 may serve as an interface that transfers input commands or data to other units included in the terminal 1200 . Also, the input/output interface 1213 may output user commands or data received from other units of the terminal 1200 .

According to various embodiments of the present invention, the terminal 1200 may further include a storage module, such as a memory, or a processor, such as a BS.

Meanwhile, FIG. 12 shows a case where the terminal 1200 is implemented as separate units such as the communication device 1100, a display 1211, and an input/output interface 1213, but the terminal 1200 ) can be implemented in a form in which at least two of the communication device 1100, the display 1211, and the input/output interface 1213 are integrated into one unit.

Also, the terminal 1200 may be implemented with one chipset.

In FIG. 12, an example of an internal structure of a terminal including a communication device in an LTE mobile communication system according to various embodiments of the present invention has been described. Next, referring to FIG. 13, according to various embodiments of the present invention An internal structure of a base station in a wireless communication system will be described.

13 is a diagram schematically illustrating an internal structure of a base station in a wireless communication system according to various embodiments of the present invention.

Referring to FIG. 13 , a base station 1300 includes a transmitter 1311, a controller 1313, a receiver 1315, and a storage unit 1317.

First, the controller 1313 controls the overall operation of the base station 1300, and in particular, controls operations related to an interference mitigation method according to various embodiments of the present invention, that is, a method of mitigating interference in consideration of CRS grouping. do. Since operations related to the interference mitigation method according to an embodiment of the present invention are the same as those described in FIGS. 1 to 10, detailed description thereof will be omitted here.

The transmitter 1311 transmits various signals and various messages to other entities, such as a communication device, under the control of the controller 1313. Here, since various signals and various messages transmitted by the transmitter 1311 are the same as those described in FIGS. 1 to 10, detailed description thereof will be omitted.

Also, the receiver 1315 receives various signals and various messages from the other entities under the control of the controller 1313. Here, since various signals and various messages received by the receiver 1315 are the same as those described in FIGS. 1 to 10, a detailed description thereof will be omitted here.

The storage unit 1317 stores programs and various data related to an operation related to an interference mitigation method according to an embodiment of the present invention, performed by the base station 1300 under the control of the controller 1313.

Also, the storage unit 1317 stores various signals and various messages received by the receiver 1315 from the other entities.

Meanwhile, FIG. 13 shows a case where the base station 1300 is implemented as separate units such as the transmitter 1311, the controller 1313, the receiver 1315, and the storage unit 1317, Of course, the base station 1300 can be implemented in an integrated form of at least two of the transmitter 1311, the controller 1313, the receiver 1315, and the storage unit 1317.

Also, of course, the base station 1300 may be implemented with one processor or one chipset.

Certain aspects of the invention may also be implemented as computer readable code on a computer readable recording medium. A computer readable recording medium is any data storage device capable of storing data readable by a computer system. Examples of the computer readable recording medium include Read-Only Memory (ROM), Random-Access Memory (RAM), CD-ROMs, magnetic tapes, and the like. , floppy disks, optical data storage devices, and carrier waves (such as data transmission over the Internet). The computer readable recording medium may also be distributed across networked computer systems, so that the computer readable code is stored and executed in a distributed manner. In addition, functional programs, code, and code segments for achieving the present invention can be easily interpreted by programmers skilled in the field to which the present invention is applied.

It will also be appreciated that the apparatus and method according to an embodiment of the present invention can be realized in the form of hardware, software, or a combination of hardware and software. Any such software may include, for example, a volatile or non-volatile storage device such as a ROM, whether removable or rewritable, or a memory device such as a RAM, a memory chip, device, or integrated circuit. , Or, for example, CD, DVD, magnetic disk or magnetic tape, such as optically or magnetically recordable and at the same time can be stored in a machine (eg, computer) readable storage medium. The method according to an embodiment of the present invention may be implemented by a computer or portable terminal including a controller and a memory, and the memory is suitable for storing a program or programs including instructions for implementing the embodiments of the present invention. It will be appreciated that this is an example of a machine-readable storage medium.

Accordingly, the present invention includes a program including code for implementing an apparatus or method described in any claim of this specification and a storage medium readable by a machine (such as a computer) storing such a program. In addition, such a program may be transmitted electronically through any medium, such as a communication signal transmitted through a wired or wireless connection, and the present invention appropriately includes equivalents thereto.

Also, the device according to an embodiment of the present invention may receive and store the program from a program providing device connected by wire or wirelessly. The program providing device provides wired or wireless communication with a memory for storing a program including instructions for causing the program processing device to perform a preset content protection method, information necessary for the content protection method, and the like, and the graphic processing device. It may include a communication unit for performing and a control unit for transmitting a corresponding program to the transmitting/receiving device at the request of the graphic processing device or automatically.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications can be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments and should not be defined by the scope of the following claims as well as those equivalent to the scope of these claims.

Claims (15)

In the chipset,
detecting an interference characteristic of a neighboring cell corresponding to one of groups configured by dividing a subframe to which at least a first reference signal region and a second reference signal region are alternately mapped;
configured to perform interference whitening on one of the groups based on the interference characteristic;
The groups divide the subframe by a first time interval occupied by the first reference signal region, divide the subframe by a first frequency band occupied by the first reference signal region, or divide the subframe by the first frequency band occupied by the first reference signal region. It is set by dividing the subframe by a second time interval occupied by 2 reference signal areas,
The second frequency band occupied by the second reference signal region is wider than the first frequency band occupied by the first reference signal region,
The second frequency band occupied by the second reference signal region is increased when a difference between interference characteristics of resource blocks (RBs) is less than a preset threshold difference,
wherein the RBs include a first time interval occupied by the first reference signal area and a resource area occupied by the first frequency band occupied by the first reference signal area.
According to claim 1,
The chipset, characterized in that the groups are set for each of the first time interval or preset period occupied by the first reference signal region.
According to claim 1,
The chipset, characterized in that the groups are set based on the difference between the first time synchronization of the neighboring cell and the second time synchronization of the serving cell.
The method of claim 1 , wherein the chipset:
detecting covariance matrices for each of the groups based on a received signal and a channel matrix;
detecting a whitening filter coefficient for each of the groups based on the covariance matrices; and
A chipset configured to perform interference whitening on the received signal and channel matrix based on the detected whitening filter coefficients.
According to claim 1,
Each of the groups includes at least one sample used to measure interference characteristics of the neighboring cell,
Wherein the at least one sample includes at least one of a reference signal, a data signal, and a control signal.
According to claim 5,
The reference signals include a common reference signal (CRS), a demodulation reference signal (DMRS), and a multimedia broadcast multicast service single frequency network reference signal: MRS), at least one of a channel status information interference measurement (CSI-IM) signal, and a channel status information-reference signal (CSI-RS),
The data signal includes a physical downlink shared channel (PDSCH) signal,
The control signal includes at least one of a physical downlink control channel (PDCCH) signal and an enhanced physical downlink control channel (EPDCCH) signal.
The method of claim 1 , wherein the chipset:
When the time interval occupied by each of the groups includes a plurality of symbols, the plurality of antenna ports transmitted in the first reference signal region, the plurality of symbols, and the plurality of symbols transmitted in each of the plurality of symbols Detecting a covariance matrix for the groups based on reference signal samples of
detecting a whitening filter coefficient for each of the groups based on the covariance matrix; and
A chipset configured to perform the interference whitening on a received signal and a channel matrix based on the detected whitening filter coefficients.
delete In a method of an apparatus in a wireless communication system,
detecting interference characteristics of adjacent cells corresponding to groups configured by dividing subframes to which at least a first reference signal region and a second reference signal region are alternately mapped; and
And performing interference whitening on one of the groups based on the interference characteristic,
The groups divide the subframe by a first time interval occupied by the first reference signal region, divide the subframe by a first frequency band occupied by the first reference signal region, or divide the subframe by the first frequency band occupied by the first reference signal region. It is set by dividing the subframe by a second time interval occupied by 2 reference signal areas,
The second frequency band occupied by the second reference signal region is wider than the first frequency band occupied by the first reference signal region,
The second frequency band occupied by the second reference signal region is increased when a difference between interference characteristics of resource blocks (RBs) is less than a preset threshold difference,
Wherein the RBs include a first time interval occupied by the first reference signal area and a resource area occupied by the first frequency band occupied by the first reference signal area.
According to claim 9,
The method of claim 1 , wherein the groups are set for each of the first time interval or preset period occupied by the first reference signal area.
According to claim 9,
The groups are set based on a difference between the first time synchronization of the neighboring cell and the second time synchronization of the serving cell.
According to claim 9,
The operation of performing the interference whitening;
detecting covariance matrices for each of the groups based on a received signal and a channel matrix;
detecting a whitening filter coefficient for each of the groups based on the covariance matrices; and
and performing interference whitening on the received signal and channel matrix based on the detected whitening filter coefficients.
According to claim 9,
Each of the groups includes at least one sample used to measure interference characteristics of the neighboring cell,
The at least one sample includes at least one of a reference signal, a data signal, and a control signal.
The method of claim 9, wherein the operation of performing the interference whitening;
When the time interval occupied by each of the groups includes a plurality of symbols, the plurality of antenna ports transmitted in the first reference signal region, the plurality of symbols, and the plurality of symbols transmitted in each of the plurality of symbols detecting a covariance matrix for the groups based on reference signal samples of ;
detecting whitening filter coefficients for each of the groups based on the covariance matrix; and
and performing the interference whitening on a received signal and a channel matrix based on the detected whitening filter coefficients.
delete

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